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  • 1.
    Ahrentorp, Fredrik
    et al.
    RISE, Swedish ICT, Acreo.
    Astalan, Andrea
    RISE, Swedish ICT, Acreo.
    Blomgren, Jakob
    RISE, Swedish ICT, Acreo.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Wetterskog, Erik
    Uppsala University, Sweden.
    Svedlindh, Peter
    Uppsala University, Sweden.
    Lak, Aidin
    Technical University of Braunschweig, Germany.
    Ludwig, Frank
    Technical University of Braunschweig, Germany.
    van Ijzendoorn, Leo J.
    Eindhoven University of Technology, The Netherlands.
    Westphal, Fritz
    Micromod Partikeltechnologie GmbH, Germany.
    Gruttner, Cordula
    Micromod Partikeltechnologie GmbH, Germany.
    Gehrke, Nicole
    nanoPET Pharma GmbH, Germany.
    Gustafsson, Stefan
    Chalmers University of Technology, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Sweden.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Effective particle magnetic moment of multi-core particles2015In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 380, p. 221-226Article in journal (Refereed)
    Abstract [en]

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy(TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems – BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm – and one single-core particle system – SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.

  • 2.
    Ahrentorp, Fredrik
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sarwe, Anna
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sepehri, Sobhan
    Chalmers University of Technology, Sweden.
    Eriksson, Emil
    Chalmers University of Technology, Sweden.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Jesorka, Aldo
    Chalmers University of Technology, Sweden.
    Winkler, Dag
    Chalmers University of Technology, Sweden.
    Schneiderman, Justin F.
    University of Gothenburg, Sweden.
    Nilsson, Mats
    Stockholm University, Sweden.
    Albert, Jan
    Karolinska University Hospital, Sweden; Karolinska Institute, Sweden.
    de la Torre, Theresa Z. G.
    Uppsala University, Sweden.
    Strømme, Maria
    Uppsala University, Sweden.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2017In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, p. 14-18Article in journal (Refereed)
    Abstract [en]

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 3.
    Blomgren, Jakob
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ilver, Dag
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sepehri, Sobhan
    Chalmers University of Technology, Sweden.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Winkler, Dag
    Chalmers University of Technology, Sweden.
    de la Torre, Tereza
    Uppsala University, Sweden.
    Strømme, Maria
    Uppsala University, Sweden.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Development of a sensitive induction-based magnetic nanoparticle biodetection method2018In: Nanomaterials, ISSN 2079-4991, Vol. 8, no 11, article id 887Article in journal (Refereed)
    Abstract [en]

    We developed a novel biodetection method for influenza virus based on AC magnetic susceptibility measurement techniques (the DynoMag induction technique) together with functionalized multi-core magnetic nanoparticles. The sample consisting of an incubated mixture of magnetic nanoparticles and rolling circle amplified DNA coils is injected into a tube by a peristaltic pump. The sample is moved as a plug to the two well-balanced detection coils and the dynamic magnetic moment in each position is read over a range of excitation frequencies. The time for making a complete frequency sweep over the relaxation peak is about 5 minutes (10 Hz–10 kHz with 20 data points). The obtained standard deviation of the magnetic signal at the relaxation frequency (around 100 Hz) is equal to about 10−5 (volume susceptibility SI units), which is in the same range obtained with the DynoMag system. The limit of detection with this method is found to be in the range of 1 pM.

  • 4.
    Gao, Shang
    et al.
    Paul Scherrer Institut, Switzerland; University of Geneva, Switzerland.
    Zaharko, Oksana
    Paul Scherrer Institut, Switzerland.
    Tsurkan, Vladimir
    University of Augsburg, Germany; Academy of Sciences of Moldova, Moldova.
    Prodan, Lilian
    Academy of Sciences of Moldova, Moldova.
    Riordan, Edvard
    Cardiff University, UK.
    Lago, Jorge
    University of the Basque Country, Spain.
    Fak, Björn
    Institut Laue-Langevin, France.
    Wildes, Andrew R.
    Institut Laue-Langevin, France.
    Koza, Marek M.
    Institut Laue-Langevin, France.
    Ritter, Clemens
    Institut Laue-Langevin, France.
    Fouquet, Peter
    Institut Laue-Langevin, France.
    Keller, Lukas
    Paul Scherrer Institut, Switzerland.
    Canevet, Emmanuel
    Paul Scherrer Institut, Switzerland; DTU Technical University of Denmark, Denmark.
    Medarde, Marisa
    Paul Scherrer Institut, Switzerland.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Giblin, Sean R.
    Cardiff University, UK.
    Vrtnik, Stanislav
    Jozef Stefan Institute, Slovenia.
    Luzar, Jose
    Jozef Stefan Institute, Slovenia.
    Loidl, Alois
    University of Augsburg, Germany.
    Ruegg, Christina
    Paul Scherrer Institut, Switzerland; University of Geneva, Switzerland.
    Fennell, Tom
    Paul Scherrer Institut, Switzerland.
    Dipolar Spin Ice States with a Fast Monopole Hopping Rate in CdEr2X4 (X = Se, S)2018In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, no 13, article id 130201Article in journal (Refereed)
    Abstract [en]

    Excitations in a spin ice behave as magnetic monopoles, and their population and mobility control the dynamics of a spin ice at low temperature. CdEr2Se4 is reported to have the Pauling entropy characteristic of a spin ice, but its dynamics are three orders of magnitude faster than the canonical spin ice Dy2Ti2O7. In this Letter we use diffuse neutron scattering to show that both CdEr2Se4 and CdEr2S4 support a dipolar spin ice state-the host phase for a Coulomb gas of emergent magnetic monopoles. These Coulomb gases have similar parameters to those in Dy2Ti2O7, i.e., dilute and uncorrelated, and so cannot provide three orders faster dynamics through a larger monopole population alone. We investigate the monopole dynamics using ac susceptometry and neutron spin echo spectroscopy, and verify the crystal electric field Hamiltonian of the Er3+ ions using inelastic neutron scattering. A quantitative calculation of the monopole hopping rate using our Coulomb gas and crystal electric field parameters shows that the fast dynamics in CdEr2X4 (X = Se, S) are primarily due to much faster monopole hopping. Our work suggests that CdEr2X4 offer the possibility to study alternative spin ice ground states and dynamics, with equilibration possible at much lower temperatures than the rare earth pyrochlore examples.

  • 5.
    Riordan, E
    et al.
    Cardiff University, UK.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Margineda, D.
    Cardiff University, UK.
    Elfassi, A.
    INSA Institut National des Sciences Appliques, France.
    Michel, S.
    INSA Institut National des Sciences Appliques, France.
    Dell'ova, F.
    INSA Institut National des Sciences Appliques, France.
    Klemencic, G. M.
    Cardiff University, UK.
    Giblin, S. R.
    Cardiff University, UK.
    Design and implementation of a low temperature, inductance based high frequency alternating current susceptometer.2019In: Review of Scientific Instruments, Vol. 90, no 7Article in journal (Refereed)
    Abstract [en]

    We report on the implementation of an induction based, low temperature, high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration allow a sample magnetic moment resolution of 5 × 10−10 Am2 at 1 MHz. We discuss the design and characterization of the susceptometer and explain the calibration process. We also include some example measurements on the spin ice material CdEr2S4 and iron oxide based nanoparticles to illustrate functionality.

  • 6.
    Sepehri, S.
    et al.
    MC2, Sweden; Chalmers University of Technology, Sweden.
    Zardán Gómez De La Torre, T.
    Uppsala University, Sweden.
    Schneiderman, J. F.
    MC2, Sweden; University of Gothenburg,Sweden.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jesorka, A.
    Stockholm University, Sweden.
    Johansson, Christer
    Karolinska University Hospital, Sweden; Karolinska Institute, Sweden.
    Nilsson, M.
    Stockholm University, Sweden.
    Albert, J.
    Stockholm University, Sweden; Karolinska University Hospital, Sweden.
    Strømme, Maria
    Uppsala University, Sweden.
    Winkler, Dag
    MC2, Sweden.
    Kalaboukhov, A.
    MC2, Sweden.
    Homogeneous Differential Magnetic Assay2020In: ACS Sensors, ISSN 2379-3694Article in journal (Refereed)
    Abstract [en]

    Assays are widely used for detection of various targets, including pathogens, drugs, and toxins. Homogeneous assays are promising for the realization of point-of-care diagnostics as they do not require separation, immobilization, or washing steps. For low concentrations of target molecules, the speed and sensitivity of homogeneous assays have hitherto been limited by slow binding kinetics, time-consuming amplification steps, and the presence of a high background signal. Here, we present a homogeneous differential magnetic assay that utilizes a differential magnetic readout that eliminates previous limitations of homogeneous assays. The assay uses a gradiometer sensor configuration combined with precise microfluidic sample handling. This enables simultaneous differential measurement of a positive test sample containing a synthesized Vibrio cholerae target and a negative control sample, which reduces the background signal and increases the readout speed. Very low concentrations of targets down to femtomolar levels are thus detectable without any additional amplification of the number of targets. Our homogeneous differential magnetic assay method opens new possibilities for rapid and highly sensitive diagnostics at the point of care. 

  • 7.
    Sepehri, Sobhan
    et al.
    Chalmers University of Technology, Sweden.
    Agnarsson, Björn
    Chalmers University of Technology, Sweden.
    Torre, Teresa
    Uppsala University, Sweden.
    Schneiderman, Justin
    Chalmers University of Technology, Sweden; University of Gothenburg, Sweden.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jesorka, Aldo
    Chalmers University of Technology, Sweden.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nilsson, Mats
    Stockholm University, Sweden.
    Albert, Jan
    Karolinska University Hospital, Sweden; Karolinska Institute, Sweden.
    Strømme, Maria
    Uppsala University, Sweden.
    Winkler, Dan
    Chalmers University of Technology, Sweden.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Characterization of Binding of Magnetic Nanoparticles to Rolling Circle Amplification Products by Turn-On Magnetic Assay2019In: Biosensors, ISSN 2079-6374, Vol. 9, no 3Article in journal (Refereed)
    Abstract [en]

    The specific binding of oligonucleotide-tagged 100 nm magnetic nanoparticles (MNPs) to rolling circle products (RCPs) is investigated using our newly developed differential homogenous magnetic assay (DHMA). The DHMA measures ac magnetic susceptibility from a test and a control samples simultaneously and eliminates magnetic background signal. Therefore, the DHMA can reveal details of binding kinetics of magnetic nanoparticles at very low concentrations of RCPs. From the analysis of the imaginary part of the DHMA signal, we find that smaller MNPs in the particle ensemble bind first to the RCPs. When the RCP concentration increases, we observe the formation of agglomerates, which leads to lower number of MNPs per RCP at higher concentrations of RCPs. The results thus indicate that a full frequency range of ac susceptibility observation is necessary to detect low concentrations of target RCPs and a long amplification time is not required as it does not significantly increase the number of MNPs per RCP. The findings are critical for understanding the underlying microscopic binding process for improving the assay performance. They furthermore suggest DHMA is a powerful technique for dynamically characterizing the binding interactions between MNPs and biomolecules in fluid volumes.

  • 8.
    Sepehri, Sobhan
    et al.
    Chalmers University of Technology, Sweden.
    Eriksson, Emil
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Zardán Gómez de la Torre, Teresa
    Uppsala University, Sweden.
    Kustanovich, Kiryl
    Chalmers University of Technology, Sweden.
    Jesorka, Aldo
    Chalmers University of Technology, Sweden.
    Schneiderman, Justin F.
    Chalmers University of Technology, Sweden ; University of Gothenburg, Sweden.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Strømme, Maria
    Uppsala University, Sweden.
    Winkler, Dag
    Chalmers University of Technology, Sweden.
    Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high-Tc SQUID magnetic readout2017In: APL Bioengineering, Vol. 2, no 1, article id 016102Article in journal (Refereed)
    Abstract [en]

    A bioassay based on a high-Tc superconducting quantum interference device (SQUID) reading out functionalized magnetic nanoparticles (fMNPs) in a prototype microfluidic platform is presented. The target molecule recognition is based on volume amplification using padlock-probe-ligation followed by rolling circle amplification (RCA). The MNPs are functionalized with single-stranded oligonucleotides, which give a specific binding of the MNPs to the large RCA coil product, resulting in a large change in the amplitude of the imaginary part of the ac magnetic susceptibility. The RCA products from amplification of synthetic Vibrio cholera target DNA were investigated using our SQUID ac susceptibility system in microfluidic channel with an equivalent sample volume of 3 μl. From extrapolation of the linear dependence of the SQUID signal versus concentration of the RCA coils, it is found that the projected limit of detection for our system is about 1.0 × 105 RCA coils (0.2 × 10−18 mol), which is equivalent to 66 fM in the 3 μl sample volume. This ultra-high magnetic sensitivity and integration with microfluidic sample handling are critical steps towards magnetic bioassays for rapid detection of DNA and RNA targets at the point of care.

  • 9.
    Sjöberg, Anders
    et al.
    Lunds tekniska högskola, Sweden.
    Blomgren, Jakob
    RISE, Swedish ICT, SICS, Imego.
    Erlandsson, Max
    RISE, Swedish ICT, SICS, Imego.
    Johansson, Christian
    RISE, Swedish ICT, SICS, Imego.
    Trådlösa fuktsensorer inom byggindustrin: en fältstudie av två trådlösa system för fukt- och temperaturmätnig2007Report (Other academic)
  • 10.
    Sriviriyakul, Thana
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Bogren, Sara
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Schaller, Vincent
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Lopez-Sanchez, Patricia
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Berta, Marco
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Grüttner, Cordula
    micromod Partikeltechnologie GmbH, Germany.
    Zeng, Lunjie
    Chalmers University of Technology, Sweden.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nanorheological studies of xanthan/water solutions using magnetic nanoparticles2019In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 473, p. 268-271Article in journal (Refereed)
    Abstract [en]

    We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration.

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